WADDEN MOSAIC

Understanding and improving the underwater nature in the Dutch Wadden Sea

Wadden Mosaic is a project that focuses on a better understanding of the underwater nature in the Dutch Wadden Sea. Specific attention is paid to the deeper parts that are permanently submerged, even at low tide: the subtidal Wadden Sea. In the coming years, researchers from the NIOZ (Netherlands Institute for Sea Research) and the University of Groningen will be mapping this underwater landscape and the associated biodiversity for the first time. In addition, they are conducting research to study the effects of potential management measures for the protection and recovery of the submerged mudflats. The project is in line with the goals of the Dutch national government to promote underwater nature.

Subprojects
There are 5 sub-projects within Wadden Mosaic, and each focusses on different nature management and restoration questions.

  • An overview of nature values of the permanently submerged mudflats is being created. What do living environments and the food web of the subtidal part of the Dutch Wadden Sea look like? Twice during the project period, the subtidal mudflat will be systematically sampled. Both abiotic characteristics (salt content, silt content, etc.), as well as abiotic aspects (species, biomass, analysis of stable isotopes) will be examined. All the data together provide a habitat map and nature opportunity map of the subtidal Wadden Sea. A visualisation of the food web will be created. With the information, a management manual for the subtidal Wadden Sea will be written. In addition, advice for monitoring methods of the subtidal Wadden Sea will be provided.
  • Restoration measure ‘Closing area’. In this sub-project, areas that have been closed off of to human disturbance, including bottom trawling fisheries, will be examined and compared to areas that are still open to human activities. The changes on the ecosystems and the food web will be examined. An experimental bottom disturbance experiment will be conducted in various parts of the Wadden Sea, varying from an area that has long been closed to an area currently being exploited.
  • Restoration measure ‘Application of hard substrate’. In this sub-project, it will be examined whether the application of hard structures possibly contributes to the quality of the underwater environment. Various types of hard substrate, for example pebbles or shells, will be applied in an experimental way and changes in the biodiversity related to these substrates will be monitored.
  • ‘Restoration of shellfish reefs. How promising are the restoration measures for shellfish reefs in the subtidal Wadden Sea? In areas that are free from exploitation, structures will be placed on which mussels and flat oysters can attach themselves as shown in other projects. The effects on the biodiversity in these areas are also being tracked.
  • ‘Restoration possibilities of seagrass meadows. In this sub-project, promising restoration measures to bring back submerged seagrass meadows in the Wadden Sea will be tested. The most promising locations for successful restoration of subtidal seagrass beds will be mapped. Next, there will be some experimental work with both artificial and natural seagrass grown from seeds and cuttings.

Shellfish reefs

Overview nature values

Seagrass meadows

Hard substrate

Closing areas

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